Renaissance Astronomy

• Ptolemy
  • Geocentric system
    • typical naive belief--we are the center of the world
  • Reflected common sense
    • Earth does appear to be the center
    • made accurate predictions of astronomical events
    • was part of Church dogma
    • fixing the date of Easter (http://www.ips.gov.au/papers/richard/easter.html)
  • Epicycles
    • were needed to explain movement of planets
    • see: http://csep10.phys.utk.edu/astr161/lect/retrograde/aristotle.html
  • Aristarchus of Samos anticipated Copernicus but was largely ignored.
    • see: http://phyhp.phy.ncku.edu.tw/~astrolab/mirrors/apod/ap971108.html
• Nicolaus Copernicus
  • Heliocentric system
  • Provided no additional accuracy
  • Published after his death because of dogma
  • Simpler system (Occam's razor)
• Tycho Brahe
  • Tried to measure universe precisely
  • Achieved his goals thanks to incredible government grant from Danish king
  • In 1572 proved that a nova was in the "eighth heaven"
  • Left Denmark and ended up in Prague where he died after housing Kepler
  • Kepler stole Brahe's data after his death
  • see: http://www.phys.virginia.edu/classes/109N/1995/lectures/tychob.html for pictures and text
• Giordano Bruno and Michael Servetus
  • Both burned for believing in Copernican system
• Johannes Kepler
  • Platonic simplicity
    • tried to force universe into a set of nesting solids
      • see: http://www.phys.virginia.edu/classes/109N/1995/lectures/kepler.html for a picture and text
  • Sun worshiper
  • Astrologer
  • Discovered that planets had elliptical orbits
  • Kept careful records of his observations
  • Stole Brahe's data
• Galileo
  • Early life
    • Leaves monastery at Vallombrosa
    • Enters University of Pisa (Arts)
      • Changes majors to mathematics
    • Receives appointment at Pisa
    • Moves to University of Padua in Venetian Republic
      • Does work in applied mathematics (fortifications, sector)
      • Discovers law of falling bodies
  • Telescope
    • did not invent but improved and marketed it
    • first views of skies with it were first step in new paradigm
  • Use of telescope
    • looked at moon first
      • noted that moon had mountains and was thus not smooth
    • looked at Jupiter
      • discovered three moons
      • named them after the Medici family
      • discovery led to 11 heavenly bodies instead of 7
      • problem because violated Aristotelian and Ptolemaic model and because it showed for the first time that a body revolved around the earth not the Sun
  • Church condemns the writings of Copernicus
    • Galileo warned not to hold, defend, or teach the Copernican model
    • Tried, years later, for teaching
  • Recanted